New study shows "pesticide cocktail" weakens bee immunity

New study shows "pesticide cocktail" weakens bee immunity

Over the past several years, the weight of the evidence linking pesticides to bee declines has grown. While pesticides are not the only factor, they are seen as a key catalyst that, in combination with other factors like disease, poor nutrition and pests, are driving bee declines. A study released this week in PLOS ONE underscores how pesticide exposure weakens bees immune systems making them more susceptible to the gut parasite Nosemaceranae.

In the new Pettis et al study, insecticides and fungicides were found in all 19 pollen samples taken from bees living in hives surrounded by 7 common crops that rely on honey bees for pollination. On average, the pollen samples included 9 different pesticides, and in one case, included 21 different pesticides.

Emily Marquez, staff scientist at Pesticide Action Network issued the following statement in response to the new study:

"The study underscores a growing body of evidence that points to pesticides as a catalyst in bee declines. While many studies have highlighted concerns around neonicotinoid pesticides, this research suggests that a chemical cocktail of several different types of pesticides can be found in pollen collected by bees, and that multiple types of pesticides — fungicides, insecticides, herbicides and miticides — can negatively impact the health of bees, both alone and in combination.

Bees often travel large distances to gather food and are needed to pollinate many crops across the country, including apples, blueberries and pumpkins. The Pettis et al study shows that bees operating in the diverse agricultural landscape can be exposed to a wide range of pesticides that can suppress their immunity. In this study, eight of the pesticides found in the pollen samples made bees more susceptible to the Nosema parasite."